Don't Worry, I'm Fine (2006)
Directed by Philippe Lioret. Staring Melanie Laurent and Kad Merad
When Lili (Mélanie Laurent, "Days of Glory") returns home from a holiday in Spain, she is distraught to learn that her twin brother, Loic, has left after an argument with their father (Kad Merad, "The Chorus"). Not believing the reason given to her and unable to comprehend why Loic has not attempted to contact her, Lili refuses to eat and ends up in a psychiatric hospital. She only returns to the land of the living when her parents, against doctors' orders, deliver her a letter from Loic telling her "Don't Worry, I'm Fine."
A great piece of French drama. Hugely dark, beautifully acted and well filmed.